Predictive performance of the common red flags in emergency department headache patients: a HEAD and HEAD-Colombia study

K. Chu, A. M. Kelly, W. S. Kuan, F. B. Kinnear, G. Keijzers, D. Horner, S. Laribi, A. Cardozo, M. A. Karamercan, S. Klim, T. Wijeratne, S. Kamona, C. A. Graham, R. Body and T. Roberts